diff --git a/services/backup/src/Tools.cpp b/services/backup/src/Tools.cpp
index 44188c3f1..33938ed57 100644
--- a/services/backup/src/Tools.cpp
+++ b/services/backup/src/Tools.cpp
@@ -1,35 +1,57 @@
 #include "Tools.h"
 
+#include "GlobalConstants.h"
 #include "GlobalTools.h"
 
 #include <chrono>
 #include <cstdlib>
 #include <random>
+#include <sstream>
+#include <stdexcept>
 
 namespace comm {
 namespace network {
 namespace tools {
 
 std::string generateRandomString(std::size_t length) {
   const std::string CHARACTERS =
       "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
   thread_local std::random_device generator;
   std::uniform_int_distribution<> distribution(0, CHARACTERS.size() - 1);
   std::string random_string;
   for (std::size_t i = 0; i < length; ++i) {
     random_string += CHARACTERS[distribution(generator)];
   }
   return random_string;
 }
 
 std::string generateHolder(
     const std::string &blobHash,
     const std::string &backupID,
     const std::string &resourceID) {
   return backupID + ID_SEPARATOR + resourceID + ID_SEPARATOR + blobHash +
       ID_SEPARATOR + tools::generateUUID();
 }
 
+std::string validateAttachmentHolders(const std::string &holders) {
+  std::stringstream stream(holders);
+  std::string item;
+  std::string result;
+
+  while (std::getline(stream, item, ATTACHMENT_DELIMITER)) {
+    if (item.empty()) {
+      throw std::runtime_error("empty holder detected");
+    }
+    result += item;
+    result += ATTACHMENT_DELIMITER;
+  }
+  if (result.empty()) {
+    throw std::runtime_error("parse attachment holders failed");
+  }
+
+  return result;
+}
+
 } // namespace tools
 } // namespace network
 } // namespace comm
diff --git a/services/backup/src/Tools.h b/services/backup/src/Tools.h
index 47fc5584b..619d66398 100644
--- a/services/backup/src/Tools.h
+++ b/services/backup/src/Tools.h
@@ -1,18 +1,20 @@
 #pragma once
 
 #include <string>
 
 namespace comm {
 namespace network {
 namespace tools {
 
 std::string generateRandomString(std::size_t length = 20);
 
 std::string generateHolder(
     const std::string &blobHash,
     const std::string &backupID,
     const std::string &resourceID = "");
 
+std::string validateAttachmentHolders(const std::string &holders);
+
 } // namespace tools
 } // namespace network
 } // namespace comm
diff --git a/services/lib/src/GlobalConstants.h b/services/lib/src/GlobalConstants.h
index 7dbd9394c..fa26224db 100644
--- a/services/lib/src/GlobalConstants.h
+++ b/services/lib/src/GlobalConstants.h
@@ -1,28 +1,28 @@
 #pragma once
 
 #include <string>
 
 namespace comm {
 namespace network {
 
 // 4MB limit
 // WARNING: use keeping in mind that grpc adds its own headers to messages
 // https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md
 // so the message that actually is being sent over the network looks like this
 // [Compressed-Flag] [Message-Length] [Message]
 //    [Compressed-Flag]   1 byte  - added by grpc
 //    [Message-Length]    4 bytes - added by grpc
 //    [Message]           N bytes - actual data
 // so for every message we get 5 additional bytes of data
 // as mentioned here
 // https://github.com/grpc/grpc/issues/15734#issuecomment-396962671
 // grpc stream may contain more than one message
 const size_t GRPC_CHUNK_SIZE_LIMIT = 4 * 1024 * 1024;
 const size_t GRPC_METADATA_SIZE_PER_MESSAGE = 5;
 
 const std::string AWS_REGION = "us-east-2";
 
-const std::string ATTACHMENT_DELIMITER = ";";
+const char ATTACHMENT_DELIMITER = ';';
 
 } // namespace network
 } // namespace comm